Optic

The MK12 Special Purpose Rifle has been around 20 plus years now give or take and has achieved an excellent reputation for accuracy and effectiveness. I won’t go over it’s history and development here except to say it was developed as a light weight sniper rifle for special operations forces. It’s use in the GWOT went on to prove it as an excellent variant of the infinitely adaptable AR15.

Since then civilian buyers have “build” copies and nearly perfect clones of the rifle. It’s been used arguably more in the civilian world than the military world at this point since it is now no longer officially used by the military. It’s proven to be an excellent precision AR15 in every way even if it is “dated” compared to the never ending marketing to selling us lighter and lighter and more and more Gucci new models and variants with debatable improvements.

One thing I have noticed about the MK12 when it comes up in discussion is the same old subject about its effective range when it comes to accuracy. A lot of people seem to think its a 600 yard gun. Of course other people who know better will shoot them further but that doesn’t seem to make much of a dent in the never ending opinions of online commenters. So once again I decided to demonstrate what it can do and push it to its extreme limits. This will be ongoing for the next few months. So let’s get started.

My first thought was to start this off with all the usual sand bags and rests and all the stuff to replicate shooting from a bench on a range to milk accuracy. Then I decided maybe it would be better if I shot the gun at long range just like it would have been used in the field, bipods and laying prone or across a pack. If I couldn’t get results from there for whatever reason I would use a bench , rest and bags.

Shooting from prone using the ATLAS bipod and no rear sand bag, I shot the rifle out to 900 yards. Target used was the official 1,000 BR target with scoring rings. I used this instead of a steel target so we would have something to actually measure by and to show results. Ammo used was the ammo developed for the SPR. The Black hills 5.56MM MK 262 ammo with 77gr. Sierra match king bullet. I cheated a bit with the optic by not using the optic issued with MK12s. In this case to better see the target and make as precise of shots as possible, I used a NightForce 5.5x-22x. This insured enough elevation as well as magnification for long range. I will be using this optic for the further testing or this series. In this first test we are looking at the MOD 1 version of the MK12. Using the KAC fore arm, a douglas barrel in 1/7 twist and the usual ops inc muzzle break. Lower is Colt with SSA trigger. Upper is Colt and Colt BCG with all the correct parts etc. Future articles will hopefully include the MOD 0.

I caught a perfect morning to do this initial testing. It was 65 degrees with no humidity and a 6 o’clock wind that wasn’t even 5mph. After fine tuning the zero, I fired 20 rounds for “record” on a fresh target.

Target above is for final record group. It wasn’t the first attempt as I needed some time to fine tune the zero and settle in after a little practice. Since I am trying to show what it can do at it’s best, I am not bothering to show you my warm up targets since they were not shot with final zero and MK262. It’s expensive so handloads stood in till I was ready.

The group probably looks as crappy to you as it did to me when i first drove down to inspect it. So to put it into perspective I put up a human like target against it since that is what the gun was meant to be used on.

Yep, I had a couple of flyers that I can’t explain. No excuse. I’m not as good as I was a couple years ago. It happens. I’m pretty happy with this. Had my spotter been my preferred partner and I shot from some sandbags I believe I may have been able to tighten this up a bit. Hand loads or the new Federal 73grain Berger gold medal load may have tightened it further. Those will be next time perhaps. I think the Q target demonstrates the ability of the MK12 with its issue ammo in knocking down human bag guys pretty well though.

In part 2 I will take the target out to the full 1,000 yards. This was my intention for part one but I anticipated terrible mirage from heat and wind and set the target up a little short. The temp and wind never did rise to the level I thought it would though and I was trying to shoot in those perfect conditions while I had the chance instead of wasting it driving back to re set the target. Next Time… 1,000 yards and maybe beyond.

I picked up the new Larue LT204 scope mount. The LT204 is a newer version of the classic cantilever LT104 mount. You can get it in 1 inch, 30mm, and 34 mm rings. Best of all, it is about $70 cheaper than the old LT104.

Instead of explaining the story behind it, let me quote Mark Larue:

Because we suspect some of our near and dear competitors have been telling Uncle Sam for years that the LaRue 3/8” adjustment wrench is the chink in our armor. We suspect this because after nearly 1 million legacy LaRue mounts in Uncle Sam’s .mil system, a system that has to be awash in 3/8” LaRue wrenches, they came out with an optic solicitation that specifically specified “tool-less adjustment”. Fine, we’ll play.

Introducing LaRue “Click Adjust Nut” aka C.A.N. ™ mount.

It’s essentially our legacy LaRue Combat Proven QD mounts, with the slight change of no wrench needed to adjust the lever to the Picatinny rail. You adjust it by “clicking” the proprietary thumb nuts, much like clicking your scope turrets. It’s very-fine click adjustment is real close to an infinite adjustment.

Something interesting is you can “count the clicks” when switching optics between different uppers, allowing you to predictably maintain the torque on each rifle (and yes, you have to keep up with the scopes clicks, but you have to do that anyhow).

Mark Larue

The tool-less adjustment is nice, but the $70 cheaper is nicer. Lets take a look at the LT204 next to a LT104.

Here you can see the finger adjustable knobs vs the nuts on the legacy mount in back. These knobs have a little resistance, and are low profile. I don’t think they would accidentally move, but they are easy to adjust.The new mount (below) has a reinforcement on the cantilever section. I have seen a couple of pictures where people have bent this on the LT104 when they dropped their rifle onto the scope.The LT204 omits the 2 smaller recoil lugs for 1 large recoil lug at the end. Looks like instead of milling pockets, they just had their endmill plunge cut for weight relief cuts.

I’m sure there will be people out there who prefer the legacy LT104, and there is nothing wrong with that, but the LT204 is a nice alternative choice.

Long ago I tried an offset Mini Red Dot on and really didn’t like it. I was using the short lived TNVC el-cheapo red dot. The red dot sucked and I didn’t like how I couldn’t use the setup left handed. I really thought the MRDS type optics were junk for a while due to my experience with the TNVC red dot.

I’ve found that there have been many times I’ve tried something, disliked it, and never wanted to do it again. I find my self plenty quick to keep bad mounting something. Well I don’t want to be someone who is so set in their ways that they ignore advancements.

A military unit running ACOG 4x Scopes with offset Micro Aimpoints

An offset sight is most popular in competitions like 3 gun where speed is the key to winning. The offset red dot is run with a magnified optic to allow the user to instantly switch between them by rotating the rifle 30-45 degrees. This is much faster than trying to dial the adjustment on a 1-4 or 1-6 power scope.

I saw in increase of popularity of using an offset Micro Aimpoint. So I figured I’d give it a try. I picked up a Larue LT724 Offset Mount during a sale, and pulled a Aimpoint T-1 off a rifle to give it a try. I put it on my 5.45 upper so that I could get some good trigger time with it. I fired a couple hundred rounds with this combination.

One of the first things I noticed when I set up the combination was that thin strip of aluminum holding the optic. I have no doubt it is strong enough during normal use, but I’d be worried about it bending if the rifle were dropped on the optic.

Adding an offset optic instantly makes a firearm a little bulkier, a fair bit wider, leaves more stuff sticking out that can catch of stuff.

Shooting with the offset Aimpoint was so much better than that old cheap MRDS from back then.

There is no argument that an offset red dot is fast.

At close range, with an AR, it isn’t hard to tilt the rifle and rapidly fire shots into a torso. Something like the offset red dot really shines when you have larger more awkward guns with higher magnification scopes.

There is a story of a Police Sniper who was carrying his bolt action sniper rifle running up some stairs to get into an overwatch position when he ended up running into the bad guy in the stairwell. As he was holding the bad guy at gun point with his sniper rifle, he realized the high magnification scope was not ideal for that.

The M110 Carbines and M110K1 had offset iron sights to give the user the ability to rapidly engage close targets.

Firearms like the long range precision rifles that might get used in close distance fight are ideal for an offset or piggyback reflex sight.

For lighter or smaller carbines, with low power optics or variable optics, the utility of the offset sights becomes questionable.

Back to the shooting.

I found turning the gun to use the offset red dot reduced the recoil control a little. Not terribly so, but enough to be noticeable.

The T-1 is high enough and out enough that I was able to use it left handed with my left eye. Had to cant the gun counter clockwise and it was awkward, but it worked. I didn’t expect to be able to do that.

The offset sight was tucked in closer to the handguard. I’ve gotten use to higher mounted optics so I found when I rotated the rifle that I had to lower my head a bit for a better sight picture with the T-1. I don’t think other people would have that issue.

An odd setup by one of the High Speed Low Drag guys. Note the offset T-1 with the Nightforce 1-8X

The offset Aimpoint Micro is a rather nice setup. Downsides are the price and width it adds to the firearm. But I think it is only worth while if you are running a higher power optic in addition to needing to make precise close range shots quickly.

Having spent time in the military and working at a public range I learned that most people don’t understand zeroing sights or optics.

I always found it humorous when some of the regulars at the range would have a new rifle or new optic and invite me to come over and try their new gun. I’d fire a shot and tell them something like, “Cool rifle, but it is impacting 4 inches left for me.” The response I would get would be a coy line much like, “Well why don’t you go ahead and dial it then.”

I like to imagine that I keep all my firearms combat ready, but realistically I would never choose to use some of them in a fight. I wouldn’t grab the 10/22 for obvious reasons. While I would trust a Garand in a fight, it would be far from my first choice. One of the most critical things I think of as part of being “combat ready” would be the simple ability to hit what you are aiming at.

I like to think of the quality of a zero on a firearm as one of several states. I don’t think I’ve seen other people talk much about this, so I want to lay out what I think it.

Unzeroed

Mechanical Zero

Battle Sight Zero (BZO) or Reduced Range Zero

Fine Zero

True Zero (or proofed zero)

Unzeroed: The least desirable state for a firearm sights to be in. Hopefully an unzeroed firearm will impact close to where you aim, but there is no way to know with out test firing or checking the bore axis to the sights against a common index.

Mechanical Zero: The sight is centered either mechanically or optically. On something like a micrometer adjustable sight, mech zero may be obtained by counting the total number of clicks and adjusting it half way. On scope you could count clicks or use a mirror to get the crosshair centered in the tube. Centering a scope via scope adjustment may not be the same as optically centering.

Generally, one a well built firearm, mechanical zero will be close to right on. On cheaply built guns, not likely. If you have something like a rifle with a 30MOA canted base for long range shooting, the mechanical zero on the scope will deviate from a proper zero because of that.

It used that a brand new, out of the bolt, Colt AR15 or M16 generally didn’t need adjustments from mechanical zero when sighting in. But as of the last few years this no longer seems to be the case.

Battle Sight Zero (BZO) or Reduced Range Zero: There are all manner of reduced range zeroing techniques. Rarely you will see 10m zeroing targets. Often reduced range zeroing in militaries is done at 25m. For the longest time the USMC liked to use 36 yards for a reduced range zero on the M16A2/M16A4. The idea of a reduced range zero is to easily reproduce a longer range fighting zero at reduced ranged. It is easier and faster to zero at 25 meters than 300. Negligible effect from wind, easier to change and inspect targets, etc. The downside is that ANY minor error at this reduced range will be magnified at farther ranges. Say if a soldier was impacting 1 inch left at 25 meters, they might completely miss a hostile enemy at 300 meters. That could cost lives.

I consider a BZO an acceptable zero. I’ve found that with a 14.5 inch AR15 firing M855, if I impact 0.3 inches low at 25 yards, I will be right on at 300 yards. This lets me quickly and easily sight in any similar carbine at the very common distance of 25 yards. I used to have a scoped rifle where my 100 yard zero was 2.6 mils different from my 25 yard zero. I could dial up 2.6 mils and be right on at 25 yards. This allowed me to double check that zero with that gun at reduced range.

A BZO often won’t give you a perfect zero for the farther distance, but they should be close enough. The now common 50/200 zero is a good example. Zeroing at 50y or 50m isn’t going to give you a perfect dead on zero at 200, but it tends be close enough for practical work.

I would not hesitate to go into combat with a firearm that has a BZO. I would prefer a finer zero, but a BZO is functional.

Fine Zero: Simply put, a fine zero is zeroed at the range the firearm is intended to be sighted in at, and is adjusted as closely to being perfect as possible. A magnified scoped rifle might be fine zeroed at 100 yards. Something like a M16A2 or M4 Carbine with CCO would be fine zeroed at 300 meters. Often people going into combat never get the chance to fine zero and must just rely on a BZO.

Sometimes you are limited by the precision of the adjustments. As an extreme example, the leaf sight on my M203. Each click of the windage knob adjust the impact by 1.5 METERS at 200 meters. So if I fire a shot and impact 1/2 METER left of my point of aim, I can’t adjust closer than that. But a fine zero will be as accurate as precise as the sights allow.

A fine zero is preferred over a BZO as it will have removed any error from the BZO and have been tested out to the preferred sighting distance.

True Zero or Proofed Zero: You don’t tend to hear about this outside of precision shooters, longer range hunters, or snipers. People who have to shoot at multiple distances, or an unexpected longer range distance may take the extra step to true or proof their zero.

This is less about the zero, and more about the knowledge and preparation the shooter has made for long distance shooting. Truing or Proofing is finding out where exactly you will hit or the adjustment you need for the various ranges you might be shooting.

Simple example, I used to shoot 565 yards with a 4x ACOG. 565 yards is about 516 meters, so I should have been able to use the 500m mark in the ACOG. Instead, with my firearm and ammo I needed to use the 600m mark to impact where I wanted to hit. Had I only relied on the stock marking I would have always missed.

While I was in the Corps, when we shot the rifle range, we would note our true zero for each distance. Windage adjustment might change due to how we held our rifles, elevation might be slightly different as well. So one persons 500 yard zero might have been setting the rifle rear sight to 5, another might need to set their A2 rear sight to 5 plus 1 click.

You might have a great gun with an a great cartridge and your ballistic calculator spits out a hold over for some distance, but when you actually shoot that distance you may find you need a different adjustment or hold over. Accounting for that is truing or proofing your zero. With out proofing, that drop chart or BDC is just a suggestion, not a fact.

A very few ballistic calculators give the ability to put in your proofing results to calculate a corrected drop chart to ensure you will hit when you need to hit.

Milkor is selling off 53 M32 Grenade Launchers there were Army trade-ins. So for a mear $15,000 you can own one too. At that price, might as well get two, one for each hand.

Shame these are not the newer, upgrade, M32A1s. Those have a 3 inch shorter barrel, and are upgraded to be able to take higher pressure rounds.

Sometimes I think I am the only person in the world that isn’t in love with the M32. My biggest complaint is that it is large and bulky. It is twice the weight of a M79, and about 4 times the weight of a M203 or M320. Whom ever carries the M32 will likely have another weapon as a primary weapon. I didn’t care for the design of the stock and the optic. The stock pivots to allow for the high angle necessary for farther shots. The stock on the one I used would flop around. I really didn’t like that. In photos and videos I’ve seen of others, the stock seems to lock in various angles, so that might have just been an issue with the unit my platoon had. The optic was good, but not great. It was just a red dot you manually had to adjust for range. I had a few complaints about the optic. First it relies on the user making an accurate range estimation. If the user is wrong they have to adjust the sight again. Secondly when firing at near maximium ranges, the optic is tilted nearly 45 degrees and is aimed right at the barrel. You then won’t be able to see the target through the optic and then have to keep both eyes open to do something like the Bindon Aiming Concept to transpose the dot and the target together.

For example, in the above pictures, you see how a 40mm is nearly at 45 degrees for a 400m shot. Using an offset sight or a multi-ranging holographic sight like the discontinued M40GL allows for easy of aiming while aiming. Putting the optic right over the barrel ended up with you pointing the optic right at the barrel.

My last gripe is a training and use issue. In the Corps, I never saw anyone able to really use one fast or efficiently. I never saw anything that made me believe that the average infantryman was going to actually load and fire 18 rounds a minute through one of these. Loading always seemed slow and awkward. But to be fair, we received these mid deployment and there was never any real training time given to them.

Still, it is a very cool weapons system. One of the biggest merits we found with it was that due to its’ spring loaded cylinder, you could advance it to the chamber you want. We sometimes loaded up (in order) 2 green star clusters, 2 parachute flares, and 2 HEDP rounds. When we had to warn locals or do escalation of force, the Marine with the M32 could easily do a snap shot firing off a green star cluster to gain people’s attention and warn them. If instead, it was night time and we needed light, they could advance the cylinder twice and fired off a parachute flare or two. Should we need the indirect fire or to strike an area target, the cylinder would be advanced to the fragmentation rounds to lay down some death.

At night, it would a whole lot of fun, and kinda handy to be able to spin in place while firing parachute flares in order to light up the sky with a new constellation, albeit a temporary one.

Still, from my experience there was nothing we did with the M32 that we didn’t do as well with the M203. We certainly didn’t miss it when we turned it back in before the end of our deployment.

All that said. If I had the money to burn, I’d buy one of these surplus guns. Hell, I’d buy two, one for each hand.